This mentored career development award will provide Dr. Carter, a fellowship-trained, practicing emergency MD with the skills necessary to become an independently funded investigator with expertise in technology enhanced adolescent behavioral interventions (i.e., m-health) to decrease substance misuse and high-risk firearm behaviors (HRFB) among youth in low resource communities. While substance use and HRFB have been overwhelmingly associated, the current literature lacks contextual data on the timing, moods, motivations and activities surrounding substance use and illegal HRFB, which is urgently needed to inform effective interventions. Further, while single-session interventions have successfully decreased lower level alcohol use and peer aggression among at-risk teens, effects were modest and dissipated over time, indicating that multisession interventions may be warranted for higher-risk youth such as the proposed population. Prior studies have shown smartphone technology is a promising tool for communicating with youth as part of remotely delivered interventions, and may provide a platform for collecting daily data to inform intervention content and tailor intervention components. Such technology also allows for wider dissemination and may be a promising method of addressing substance use/HRFB among urban youth from low-resource communities. To fill critical gaps in the literature, as well as achieve long-term career goals, Dr. Carter will complete the following training aims under guidance from a multidisciplinary team of researchers: 1) Develop skills to utilize emerging technologies as a platform to collect data on substance use/HRFBs, as well as to deliver tailored intervention content; 2) Acquire skills for the design, conduct, and analysis of longitudinal trials involving daily data; 3) Further training in the development & implementation o adolescent interventions for substance use and HRFBs; and 4) Receive training in the responsible conduct of research. Training aims are closely aligned with two research aims: 1) To develop and pilot a smartphone assessment tool for daily contextual data collection of cognitive factors (i.e., moods, motives), substance use (i.e., type, amount), and HRFB in a 3- month longitudinal study [n=50] of ED youth [ages 16-24] with past 6-month substance misuse & firearm possession to assess acceptability and feasibility of daily smartphone behavioral assessments and gather data to inform intervention development; 2) To develop and pilot test an m-health intervention, as compared to enhanced usual care [n=70; 35/group], with eligible youth to assess intervention acceptability, feasibility, and fidelity, as well as trends towards decreased substance use, HRFB and criminal justice involvement. The proposed intervention includes MI-informed multisession therapy delivered by a remote therapist over a smartphone and supported by an APP to facilitate therapist contact, conduct daily assessments, provide tailored positive messages, and deliver therapist guided cognitive skills modules. Pilot data will aid in refining and clarifying content for a future fully powered randomized control trial of the intervention (i.e., R01 proposal).